MR-J4-B absolute-position batteries: confirm the model and data-retention conditions before replacement

When an absolute-position system displays a battery-related message, first identify the component, battery type and full alarm text. Applying either “switch off before replacing the battery” or “replacement must be powered” to every machine overlooks model-specific requirements. This article is limited to MR-J4-B and the RJ configurations listed in the cited manual. It explains what to check when planning replacement and does not replace site electrical-work procedures.

Distinguish the purposes of the battery units

Section 11.8 of SH-030106ENG-T distinguishes the MR-BAT6V1SET for backing up absolute-position data, the MR-BAT6V1BJ for separate transportation, and battery cases for multi-axis backup. Section 11.8.2 also states that turning off control power while replacing the MR-BAT6V1SET causes absolute-position data to be lost, while the main circuit must be de-energized as required and its stored-energy state confirmed. This distinction is not a universal battery-replacement procedure for all Mitsubishi equipment.

Prepare a checklist before shutdown

Record the full amplifier model, motor model, battery or battery-case model and their connections. Identify each axis on a multi-axis machine; batteries in the same cabinet do not necessarily serve the same purpose. For procurement, check the compatibility table, production information and existing installation. A matching plug or similar nominal voltage does not establish interchangeability.

Also save the existing alarms, reference-position or absolute-position status, and any available equipment backups. Backup files and mechanical-position records serve different purposes. Having a parameter backup does not mean that lost absolute-position data will necessarily recover automatically.

Have the responsible personnel confirm working conditions

• Identify the machine's main-circuit and control-power arrangement. Electrical personnel familiar with the equipment should establish the work sequence.
• Confirm that the mechanical load is properly held and that maintenance operations will not cause unintended movement during the shutdown.
• Consult the battery-replacement section for the actual model to identify which supplies must remain on, which must be disconnected, and the verification conditions.
• Prepare a recovery plan and assign responsibility in case data is lost. Do not rush to remove the old battery before the necessary conditions are in place.

A cleared message is not sufficient after replacement

Record the replacement model, date, personnel and alarm changes, then confirm the position status according to the machine's procedures. If an absolute-position abnormality remains, save the screen and hand it over for investigation; do not arbitrarily reset the reference position merely to suppress the message. Verification involving machining coordinates should be performed together with the person responsible for the machine.

If the motor is also to be removed or replaced, first consult vertical-axis holding and maintenance limits for an approach to checking the mechanical condition. The MR-J5 motor information there does not replace the manual for the actual MR-J4 equipment. An exact model and complete alarm are more useful for planning than simply asking the battery voltage.

Reference: MR-J4-_B_(-RJ) Servo Amplifier Instruction Manual, SH-030106ENG-T, §11.8.1 and §11.8.2, printed pages 11-56 to 11-57. This article explains applicability and suggests how to organize site information. Perform specific work according to the documentation for the actual equipment and its machine builder.